This invention relates to a delivery device for delivering signatures in a partially overlapped state, discharged from a folding machine of a rotary printing press and sent to a stacker wherein one of each double fold signatures is lagged in the direction of conveyance.
A web printing press is usually provided with a folding machine which cuts a web of printed paper into predetermined lengths and folds the cut lengths, and the folding machine is usually provided with a stacker which aligns and stacks signatures or sections sent thereto from the folding machine. The stackers are classified into vertical types in which signatures are stacked vertically and horizontal types in which the signatures are stacked horizontally.
FIG. 1 is a diagrammatic side view for explaining the conveyance of signatures to a horizontal type stacker and the stacking of the conveyed signatures on the stacker. The signatures 3 discharged onto a conveyor belt 2 by an impeller 1 provided for the paper discharger of a folding machine are overlapped one upon the other so that for example one signature 3B slightly overlaps the preceding signature 3A. The signatures 3 conveyed by the conveyor belt 2 in a partially overlapped state are clamped between a belt 6 passing about a rotary signature feeding cylinder 5 and an endless belt 7. As the belt 6 leaves the feeding cylinder 5, it runs beneath the stacker 4. At the stacker 4, the signatures are stacked such that each succeeding signature 3D is placed beneath a previously stacked signature 3C.
The signatures cut and folding by the folded machine can be of many different types depending upon the number of pages and the method of folding. Examples include type 3E shown in FIG. 2a in which two printed sheets each containing two pages are folded, and type 3F as shown in FIG. 2b in which two printed sheets each containing four pages are folded. The signatures 3E and 3F are discharged and conveyed in a partially overlapped state as shown respectively in FIGS. 2c and 2d. However, it should be understood that two printed sheets containing 2 or 4 pages constituting a single signature 3E or 3F are not displaced each other.
Where two fold signatures 3E or 3F are sent to the stacker 4 in a manner described above, the following troubles are encountered. More particularly, by taking the signature 3E as an example, when a succeeding signature 3E2 is inserted beneath a previously stacked signature 3E1 as shown in FIG. 3 the bottom sheet 3E2a constituting the lowermost signature is in contact with the paper feed belt 6 but the upper side sheet 3E2b is not in contact with the paper feed belt 6.
As a consequence these sheets are fed at different speeds so that the edges of the stacked sheets becomes offset and thus are not neatly aligned in the vertical direction. For this reason, it has been necessary to resort to frequent manual alignment of the bundle of signatures being stacked on the stacker.